Question - changing sprockets

Scort · 3 Jul 2010 at 22:28

Whilst I'm off Googling this, I thought I'd ask the learned forum members:

After reading an article recently on the R1, it’s been said that the first gear on my year (possibly before too) is very tall – I know for a fact it’ll do 102 as it hits the limiter; I found that out on an air strip by the way!

Said article listed one of the best improvements you could make to the bike is to change the front sprocket…

Whilst out on a group ride the other month, we were talking about modifications as you do and a friend of a friend said that by dropping a tooth at the front, you can up the revs, but keep the same speed; the sacrifice will come from losing top end speed. This sounded great, as I often have to feather the clutch for slow speed stuff, so if the revs are up, I can lose that chore!

I think this ties in with what I already read, and as front sprockets are fairly cheap, it seems like a pretty decent modification to try next – said FOAF also mentioned that by only changing the front, the existing chain can be re-used without having to remove links; just need to adjust the blocks again. Although he did say that changing the rear will result in a new chain, or removal (additon maybe) of links to the existing chain.

So OcUKers, might I trouble you for answers to these questions:

1. Will changing my front sprocket from the OEM 17 teeth to 16 help, if so how?
2. After making said change, will my existing 118 link chain be ok?

I understand that the speedo will be out, so I may invest in a speedo healer (how do they work by the way?) or at the very least get someone to pace me on a long straight road with sat nav and check the bike at 30, 40, 70 etc etc.

So yeah, answers, experience and pros/cons all welcome

ShakenNstirred · 3 Jul 2010 at 22:39

speedo shouldn't be out
by having a smaller front spocket you will have less top speed but better acceleration though the gears

Scort · 3 Jul 2010 at 22:44

Thanks ShakenNstirred

From a few things I have just read, most people said they fit the OEM front sprocket from the 98-03 R1, as it has 16 teeth but also some rubber damping, which apparently reduces noise; can’t say I’ve ever noticed noise specifically from that area of the bike – the whole damn thing is noisy

As for the speedo, one guy said that after changing just the front on his 07 R1, the speedo was out by 13% - said it was out by 7% even before he’d started :eek:

ShakenNstirred · 3 Jul 2010 at 22:52

its just that if your speedo read 50mph at say 3000rpm with the 17 tooth
it will now read lower with the 16 for the same rev`s but it doesnt mean the speedo is out more, its just the gearing is lower so less speed for the same rev`s

Draeger · 3 Jul 2010 at 22:54

General rule of thumb is go down a tooth on the front and up 2 teeth on the rear.

Aprilia RSV Mille gearing is 17/42 stock. I went up two teeth on the rear to a 44t Gold Renthal and was seriously amazed at the difference in grunt it afforded. It's a common mod. Then I went one tooth down on the front in combo with the 44t rear. Mindblowing. :eek:

It's like someone has bolted on an engine mod that gives another @50bhp. The difference is that noticeable. The RSV isn't exactly short of torque/low and mid range grunt from stock but the sprocket mods make it even better. Instant pickup in any gear for overtaking with instant power available on tap no matter where you are in the rev range. Mine now pops a wheelie with the slightest sniff of the throttle in 1st, 2nd and even 3rd gear easily. In short, best mod as far as "bang per buck" you can make. Drops off top speed a little but then again, who needs 175mph?. I'd rather have more urge in the "real world" on the road performance area.

As far as speedo accuracy, not sure about the R1 but Aprilia speedos are famous for being seriously accurate. Ape speedos take their pickup from a sensor at the rear which reads of the bolts on the rear disc in an optical kinda fashion. Very accurate although not particularly reliable. I've been through 3 speedo sensors since I have owned the bike. They seem to have quite a short lifespan for no reason at all.

Scort · 3 Jul 2010 at 22:55

Cool, thanks

Scort · 3 Jul 2010 at 22:59

Draeger said:
General rule of thumb is go down a tooth on the front and up 2 teeth on the rear.

Aprilia RSV Mille gearing is 17/42 stock. I went up two teeth on the rear to a 44t Gold Renthal and was seriously amazed at the difference in grunt it afforded. It's a common mod. Then I went one tooth down on the front in combo with the 44t rear. Mindblowing.

It's like someone has bolted on an engine mod that gives another @50bhp. The difference is that noticeable. The RSV isn't exactly short of torque/low and mid range grunt from stock but the sprocket mods make it even better. Instant pickup in any gear for overtaking with instant power available on tap no matter where you are in the rev range. Mine now pops a wheelie with the slightest sniff of the throttle in 1st, 2nd and even 3rd gear easily. In short, best mod as far as "bang per buck" you can make. Drops off top speed a little but then again, who needs 175mph?. I'd rather have more urge in the "real world" on the road performance area.

As far as speedo accuracy, not sure about the R1 but Aprilia speedos are famous for being seriously accurate. Ape speedos take their pickup from a sensor at the rear which reads of the bolts on the rear disc in an optical kinda fashion. Very accurate although not particularly reliable. I've been through 3 speedo sensors since I have owned the bike. They seem to have quite a short lifespan for no reason at all.

So the -1 at the front will give me more revs for the same speed, what does the +2 at the rear do then; more torque?

I think if you have a speedo sensor on the wheel, as you do, then you don't have to worry about issues, as I understand it's when the sensor is at the engine.

ShakenNstirred · 3 Jul 2010 at 23:04

2 up on the rear is the same as going down 1 at the front

Draeger · 3 Jul 2010 at 23:07

Scort said:
So the -1 at the front will give me more revs for the same speed, what does the +2 at the rear do then; more torque?

Nah m8, as far as I know the +2 at the rear simply further changes the gearing again to give a different power delivery. I'm pretty sure that actual torque figures themselves as in output from the engine dont change, it's just the way the power is delivered down on to the tarmac through your hoops that changes because of the gearing. Not sure how to explain it, that's probably as clear as mud.

Some track daft guys on RSV's I know have gone down to 15t on the front and say it pays dividends. Haven't tried that on the road myself though.

On a Mille, 16/44 is about the most common performance/gearing mod that most folk do. On the RSV forums I'm on I recommend it to all "newbies" asking about more power and so far, none have looked back.

ShakenNstirred · 3 Jul 2010 at 23:16

as most never use the top speed of there bikes
you may as well lower the gearing to give you better acceleration though the gears

jaybee · 3 Jul 2010 at 23:22

I went 2 up on the rear of my GSXR 600 and loved it. Thing with that bike though and most 600s, is that they are revvy enough as they are so this takes that to the extreme and you have to shift even quicker. Great for a blast and power wheelies in second off crests, along with instant added pickup in any gear. However, it did get tedious cruising at a high speed with higher revs, especially on commutes where it kills economy even more. Yeah I know, nobody buys a sportsbike for mpg, but I'm just saying. To be honest if I did it again, I would probably go 1 up on the rear instead of 2. However, in the OPs position with an R1 I would totally go atleast either 2 up on the rear, or 1 down on the front. I wouldn't agree with the "general rule" being said to be 1 down plus 2 up, as that's a bit lairy tbh, especially on a mille! I know what you mean about the R1 and it's tall first. My mate used to get tired of riding his in traffic constantly feathering the clutch. I've ridden it and was amazed what speed/distance you are doing by the time you have simply let the clutch fully out. In a way it's nice to be able to go that fast lazily without changing gear, but as you know it's a bit wild with the torque of 1st gear, plus it can feel like you bog down compared to other stuff unless you slip the clutch.

So to summarise, yeah I would go 1 down on the front. You can re-use your chain, but think of it as a great time to replace it with an uprated one if it needs doing since it will all be apart. You will need a good chain breaking/joining tool. Worthwhile investment if you plan to do yours and your mates yourself form time to time. Got mine for about £30 I seem to recall off ebay actually. Be prepared if doing it yourself. Prep and take your time and be armed with correct and tight fitting socket for the front nut, preferably with a 6 sided impact socket and 2 foot breaker bar. I'm sure you can find a nice guide on an R1 forum but it's pretty easy if you have a good stand (I used to use an ABBA one and would recommend them) and use a good method to keep the rear wheel locked in place as you undo the front nut. i.e. get mate to apply brakes or my preferred one is to wedge something in between the wheel spoke and frame (without marking it).

The speedo will be affected. When I did mine I got a speedo healer and it was easy to adjust. I used your described method of satnav basically. I'd recommend you get it done rather than muck about guessing speeds. Put your mind at rest so you can enjoy it.

Don't get confused (you seem to be above?) that there is a different characteristic between front and rear sprocket mods. It's about the end result of the gearing in general. Does not matter which end you make alterations on. It's about altering the overall gearing. You'll notice it the instant you ride the bike having made the change. Where you used to need to kick down to overtake say (not that you would get that in an R1 much!) you can just roll on at the same speed as the revs will already be higher for the same given speed.

As for Aprilia speedos, I remember my RS125 speedo used to break on a monthly basis. I'd never buy an Aprilia again tbh!

Parts were a nightmare to get hold of for me personally and they can be unreliable.

Scort · 3 Jul 2010 at 23:27

ShakenNstirred said:
as most never use the top speed of there bikes
you may as well lower the gearing to give you better acceleration though the gears

Agreed, I wouldn't mind losing the top end, as I keep wanting to see what the limiter in 6th looks like (only saw an indicated 185 to date - but that's windy enough).

jaybee · 3 Jul 2010 at 23:38

I'd say the two best value mods you can do on a bike in my experience are sprocket change and a QAT (quick action throttle).

Scort · 3 Jul 2010 at 23:40

jaybee said:
I went 2 up on the rear of my GSXR 600 and loved it. Thing with that bike though and most 600s, is that they are revvy enough as they are so this takes that to the extreme and you have to shift even quicker. Great for a blast and power wheelies in second off crests, along with instant added pickup in any gear. However, it did get tedious cruising at a high speed with higher revs, especially on commutes where it kills economy even more. Yeah I know, nobody buys a sportsbike for mpg, but I'm just saying. To be honest if I did it again, I would probably go 1 up on the rear instead of 2. However, in the OPs position with an R1 I would totally go atleast either 2 up on the rear, or 1 down on the front. I wouldn't agree with the "general rule" being said to be 1 down plus 2 up, as that's a bit lairy tbh, especially on a mille! I know what you mean about the R1 and it's tall first. My mate used to get tired of riding his in traffic constantly feathering the clutch. I've ridden it and was amazed what speed/distance you are doing by the time you have simply let the clutch fully out. In a way it's nice to be able to go that fast lazily without changing gear, but as you know it's a bit wild with the torque of 1st gear, plus it can feel like you bog down compared to other stuff unless you slip the clutch.

So to summarise, yeah I would go 1 down on the front. You can re-use your chain, but think of it as a great time to replace it with an uprated one if it needs doing since it will all be apart. You will need a good chain breaking/joining tool. Worthwhile investment if you plan to do yours and your mates yourself form time to time. Got mine for about £30 I seem to recall off ebay actually. Be prepared if doing it yourself. Prep and take your time and be armed with correct and tight fitting socket for the front nut, preferably with a 6 sided impact socket and 2 foot breaker bar. I'm sure you can find a nice guide on an R1 forum but it's pretty easy if you have a good stand (I used to use an ABBA one and would recommend them) and use a good method to keep the rear wheel locked in place as you undo the front nut. i.e. get mate to apply brakes or my preferred one is to wedge something in between the wheel spoke and frame (without marking it).

The speedo will be affected. When I did mine I got a speedo healer and it was easy to adjust. I used your described method of satnav basically. I'd recommend you get it done rather than muck about guessing speeds. Put your mind at rest so you can enjoy it.

Don't get confused (you seem to be above?) that there is a different characteristic between front and rear sprocket mods. It's about the end result of the gearing in general. Does not matter which end you make alterations on. It's about altering the overall gearing. You'll notice it the instant you ride the bike having made the change. Where you used to need to kick down to overtake say (not that you would get that in an R1 much!) you can just roll on at the same speed as the revs will already be higher for the same given speed.

As for Aprilia speedos, I remember my RS125 speedo used to break on a monthly basis. I'd never buy an Aprilia again tbh! Parts were a nightmare to get hold of for me personally and they can be unreliable.

That’s an excellent reply jaybee, thank you

Not that I’m saying the former weren’t mind you

It's a lot clearer from what has been posted in this thread, along with reading up elsewhere, I'm pretty keen on going -1 at the front and grabbing a speedo healer - a great mod (by the sounds of it) for about £100, not bad

I have a mate who’s a trained mechanic and has changed the sprockets on his K5 Gixxer 600, so has the tools to do it, and better still, a lovely Porsche main dealer’s workshop to use

Failing that, he can bring his bits to mine and I’ll bump the bike onto the Abba stand (great stand by the way – got it for my Ninja before), then I’ll pay him in cash and beer tokens!

Ta muchly guys, been a right result

Scort · 3 Jul 2010 at 23:42

jaybee said:
I'd say the two best value mods you can do on a bike in my experience are sprocket change and a QAT (quick action throttle).

The latter has always crossed my mind, but it's rare I hit the stopper on the R1 - even at half throttle the thing is ballistic, and when I do hit the stopper and the YCCT decides to give the engine it's all; it's like Marty McFly hitting 88 mph

Scary ****!

Draeger · 4 Jul 2010 at 00:10

jaybee said:
As for Aprilia speedos, I remember my RS125 speedo used to break on a monthly basis. I'd never buy an Aprilia again tbh! Parts were a nightmare to get hold of for me personally and they can be unreliable.

PB mag did a speedo comparison between major manufacturers a while back and Ape's came out top. Mind you, you mention an RS125 so I'm not surprised that wee tiddler put you off Aprilia ownership.

Litre Aprilias are seriously reliable but sssshhhh.......us Mille owners like to keep that to ourselves.

Dogbreath · 4 Jul 2010 at 00:31

ShakenNstirred said:
2 up on the rear is the same as going down 1 at the front

Not unless the rear sprocket has twice as many teeth as the front!

The smaller a sprocket, the more chain wear you get (since the links have to articulate further), so going larger at the rear is preferable to dropping teeth from the front.

jaybee · 4 Jul 2010 at 00:42

Dogbreath said:
Not unless the rear sprocket has twice as many teeth as the front!

The smaller a sprocket, the more chain wear you get (since the links have to articulate further), so going larger at the rear is preferable to dropping teeth from the front.

I forgot to mention that, yeah this is why you normally hear of people going bigger on the rear.

ShakenNstirred · 4 Jul 2010 at 01:52

Dogbreath said:
Not unless the rear sprocket has twice as many teeth as the front!

The smaller a sprocket, the more chain wear you get (since the links have to articulate further), so going larger at the rear is preferable to dropping teeth from the front.

yeah but we wasnt on about that
i was saying that you get about the same top speed drop

Flukester · 4 Jul 2010 at 09:07

I run a 16 front on the ZX10 from the stock 17....

After the change gives a increase of about 20 butt bhp, the difference is amazing.... downside is bike revs out at 174mph, but hey thats plenty and it gets there so fast now you wont be needing more

. Fuel economy on long journeys is also worse, but who cares

Launching the bike from standstill becomes VERY easy, no bog downs, and best bit of all she power wheelies without clutch in 2nd and 3rd with a tug

I then fitted a speedohealer and done a GPS cal on it, currently set at about -14%, which is the gearing change, normal speedo inaccurancy and tyre profile change I'm running.

Speedo is set accurate at 100mph...

Current chain has lasted about 13000 miles and needs replacing, so it doesn't effect chain life that much as thats about right for a sports bike chain.